Quadrature local oscillator signal sources are used in the down conversion and processing of received signals in a receiver. Such devices typically include a frequency synthesizer and a 90.degree. power splitter for generating an in-phase and a quadrature-phase signal. While such prior art devices have proven generally effective for non-precision applications, they typically produce small, but significant, amplitude and phase errors in the generated quadrature signals. The amplitude errors typically arise from non-linearities in the frequency synthesizer, while phase inaccuracies in the phase splitter produce the phase error between the in-phase and quadrature-phase signals such that these signals do not always have an exact 90.degree. phase difference. Such errors eventually degrade the overall signal-to-noise ratio of the receiver output, thereby preventing use of the receiver in high precision applications.
Accordingly, there is a need for an improved signal generator which produces accurate quadrature signal outputs for use in high precision receiver applications.